tacsail.be has developed a free utility to convert BSB files to MapLib format.

From the author -->

I wrote a free small tool which converts unencrypted NOAA RAster charts to MapLib. Read the remarks in the install procedure on how to use it. It is quite straightforward in usage. On Vista you should set the properties to administrator, right click on the exe file in the program folder. You can download it from my website www.tacsail.be.